HP XP P9500 Storage - Manual (Page 31)

Consistency times and consistency delta values
This section describes consistency times and consistency delta values. By referencing consistency
time and consistency delta values, you can check the RPO (recovery point objective), which shows
when data was written to the S-VOL, and the delay status of data transfers.
Description of consistency times and consistency delta values and how to use them.
Table 2 (page 31) describes consistency times and consistency delta values and how to use them.
Note that the timestamp is a record of the time data was written to a P-VOL from a host.
Table 2 Description of consistency times and consistency delta values and how to use them
How to use Description Item
The value will not be updated in SUSPEND
status. As a result, RPO can be checked
with this value. The most recent timestamp for data whose consistency is
preserved in a consistency group. This value is the most
recent timestamp of data that has successfully reached the
remote site. Consistency
time
This value differs based upon the setting of C/T TIME MODE.
The possible values can be:
• C/T TIME MODE: JOURNAL
The most recent timestamp associated with data that
has arrived at the restore journal for this consistency
group.
•
C/T TIME MODE: VOLUME
The most recent timestamp associated with data that
has been applied to the S-VOLs for this consistency
group.
In the DUPLEX status, the value represents
the approximation of the data differences The time delta (difference) between consistency time and
the current time when the YKQUERY command was issued.
1
Consistency
delta
for P-VOL and S-VOL. For this reason, you
can use it in the following cases:
•
An indication of whether the RPO is
being met in the DUPLEX status. (For
EXCTGs, use the EXCTG consistency
delta value to approximate the
differences between the P-VOL and
S-VOL data.)
•
An indication of the network data
transfer delay with EXCTG in the
DUPLEX
status.
The value will not be updated in the
Suspend
status. Using this value, you can
The most recent timestamp for data whose consistency is
preserved in an extended consistency group.
This value is a timestamp (10:00:02 of Figure 6 (page 30) )
that is used in arbitration processing.
EXCTG
consistency
time
determine whether the RPO is being met
for the EXCTG when in Suspend status.
In the Suspend status, the value is based
upon the most recent timestamp associated
EXCTG consistency time is used in arbitration processing
and is the oldest write timestamp among the most recent
with data that has arrived at all of the
write timestamps of update journal data from the
consistency groups.
restore journals for all of the consistency
groups in the EXCTG.
In the DUPLEX status, this value provides
an approximation of the data differences The time delta (difference) between an EXCTG consistency
time and the current time when the YKQUERY command
was issued.
1
EXCTG
consistency
delta
between the P-VOLs and S-VOLs in the
EXCTG. Using this value, you can
determine whether the RPO is being met
for the EXCTG when in the DUPLEX status.
Grouping to simplify volume operations 31